Synchronizing engines on a twin

Hi, Does anyone knows if it exist a system to synchronize the two glow engines of a twin (like a p38).

It must not be Master/Slave based because, the slave may fail, and the master will not idle in this case. At least, the system should stop the remaining engine if one fail;

I imagine a system with optical sensor to get the rpm of each propeller.

Thanks Regards

It is not necessary to synchronize the engines to the degree you want. I have three twins and here is what to do. Adjust each engine to rich side of peak about 200 rpms. Richen the weaker engine to the other engines rpms. All of mine are within 200rpms of each other anyway and I don't have to do this proceedure although I check it each flying sesson. You will not notice even if one engine is acting up to even

1000 rpms if your speed is high. If this is your first twin, remember, engine out cannot be corrected with ailerons. Practice using the rudder. An engine out is a yaw problem not a roll problem. If you have and engine out, keep wings level with the rudder, turn only towards the live engine if possible and keep plenty of speed up or your rudder control will not save you. Good Luck Gene

Hi,

If you think it could be RCM, in which country ? I look on google and theses "R.C.M" magazine exists in many countries. So which one ?

Any information will be really appreciated !!!

Regard MLD

"Hugh Prescott" a écrit dans le message news:

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Greetings

Just found the article in my files at work.

Title: Electronic Sync System For Twins Author: Joe Utasi Published in Model Aviation, October 1982

Printed circut boards were avialable form Jomar Products at the time of publication. Would be simple to layout in Eagle PCB designer and do a toner transfer to copper clad and etch. It is single sided, no surface mount, no microprocessor design.

Requires the high throttle pulse to be a long pulse. Draws 16-17 ma at 4.8 volts. Uses two Hall effect sensors and magnets in spinner backplate. Sync's engines RPM not crank shaft position. Cuts in at 2500 RPM.

Circut board would be aprox size of a modern receiver and just plugs in to receiver throttle channel and then plug each throttle servo into the sync board.

Article has a nice discription of how the circut works and mods / tuning you can make.

This was one of several electronic projects that Joe developed and had published in MA. Don't know if Joe or Jomar are still around.

Hugh

RCM= RC Modeler

Joe sold his company years ago and it is now called EMS. I believe that his sync was based on master/slave but I have never actually used one on any of my multi-motor projects Have an on-line read....

Just checked the EMS JOMAR site and the sync box is listed.

Looking at the photo of it's circut board it appears to have been converted to surface mount componets.

No indication of a discription of the circut and custom mods.

Hugh

I've used one it works fine, I have my second one about to go into another twin. Sparky

Can you confirm that if the slave engine stop for instance, the master engine is not affected ?

I imagine so, because of the Master/Slave principle. MLD

"Elmshoot" a écrit dans le message news: snipped-for-privacy@mb-m03.aol.com...

Yes, as another poster said. If the master sags the slave will follow if the slave sags you will get a yaw from asymetrical power as well as you will hear the engines go out of sync. What is neat and I know it will work but have never tried it that as long as you use the same props on the engines the engines DO NOT have to be the same displacement . A good example is using a .40 as the master and using a .46 as the slave all spinning a 10x6 or similar prop. It is a nice system it does take a little time to set up but it is trouble/maintenance free once it is set up. Sparky

Don't you mean richen the "stronger" (higher RPM) engine to match the weaker?

There was a system many moons ago. Don't recall who made it.

It involved mounting small button magnets on the back plate of the spinners. Then positioning a hall effect sensor (mag tape head is one example) behind each spinner so that it sensed the passage of the magnets. This provides an RPM reading from each engine. It then went to a control box which controlled the two engine servos to match the RPMs. There was a master slave relationship with the slower engine being the master. That way the system would not constantly try to bring the slower engine up to the faster engines RPM when at full throttle.

There was also a fail safe mode. In the event of an engine failure, the system would sense the RPM having dropped below a predetermined level and disconnect the slave feature. Thus allowing the remaining engine to continue under normal control.

I seem to recall that price and the fact that it was a novelty rather than a necessity kept sales too low to stay in business.

I believe it was Jomar.

Its the same novelity as high quality servos vs. sport servos. The system works ok but when you hear a twin in full sync ALL the time. You will agree that it is a very nice system to have. It is a low sale item but EMS still has them. Sparky

Yes I did mean that. Thank's for finding my mistake. Sorry. Gene

Hi All,

A french engineer is doing the system I wanted last year :D ! (An much more, sequencer for gears, flaps, servo slower ... etc ...)

It's not a master-slave system, but it would synchronise engines b slowing down the faster, and accelerate the slower. And the option t stop the surviving engine automaticaly.

The system is configured by a tool under windows freely downloadable.

I don't try it yet. The developper is looking for beta testers.

See at the bottom of

for englis version

ML

-- ML

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No synchronizing problems when flying an electric twin. Two _brushless_ motors controlled by one controller, will always be in PERFECT sync.

Vriendelijke groeten ;-) Ron van Sommeren near Nijmegen, the Netherlands

----- Original Message ----- From: "MLD" Newsgroups: rec.models.rc.air Sent: Tuesday, May 24, 2005 7:42 AM Subject: Re: Synchronizing engines on a twin

...provided they start at all... ;-)

A lot of twin combo's do start. According to the rules they shouldn't, but they do, provided there's little spread in the motor and prop parameters. Bastards them is ;-)

Vriendelijke groeten ;-) Ron van Sommeren near Nijmegen, the Netherlands